JQuery code to manually tick a list lookup value [Display format: Check boxes (Multiple-Selection)] don't seem to work any more after installing Nintex forms v2.7.0.0 update

[#1]

Hi All,

   After upgraded Nintex Forms version 2.7.0.0 is installed, I realise that JQuery code to tick a checkbox in a list lookup (Display format: Check boxes (Multiple-Selection)) on Nintex Form don't work any more.

For Example,

Client ID JavaScript variable: LookUpControlJSName

Form - Custom JavaScript:     NWF$("#"+LookUpControlJSName).find("input")[0].checked=true;

Does anyone have this problems?  Does anyone have a solution to this?

In previous version, the above line used to work.  It tick the first checkbox of the list lookup (Display format: Check boxes (Multiple-Selection)).

Now I get an error below on that line:

"Unable to set property 'checked' of undefined or null reference"

Would be greatly appreciated if anyone can tell me how I can tick a checkbox in a list lookup via JavaScript/JQuery on Nintex Forms version 2.7.0.0.

Thanks in Advance.